Chapter 15_ The Lung: Pulmonary Edema

Question 1

Pulmonary edema can
result from :

Answer 1

hemodynamic disturbances (hemodynamic or cardiogenic pulmonary edema) or
from direct increases in capillary permeability , as a result of microvascular injury ( Table 15-1 ).
Therapy and outcome depend on the underlying etiology.

Question 2

TABLE 15-1 – Classification and Causes of Pulmonary Edema

Answer 2

• HEMODYNAMIC EDEMA
• EDEMA DUE TO MICROVASCULAR INJURY (ALVEOLAR INJURY)
• EDEMA OF UNDETERMINED ORIGIN

Question 3

TABLE 15-1 – Classification and Causes of Pulmonary Edema

What can cause HEMODYNAMIC EDEMA?

Answer 3

Increased hydrostatic pressure (increased pulmonary venous pressure)

• Left-sided heart failure (common)
• Volume overload
• Pulmonary vein obstruction

Decreased oncotic pressure (less common)

• Hypoalbuminemia
• Nephrotic syndrome
• Liver disease
• Protein-losing
• enteropathies

Lymphatic obstruction (rare)

Question 4

TABLE 15-1 – Classification and Causes of Pulmonary Edema

What can cause EDEMA DUE TO MICROVASCULAR INJURY (ALVEOLAR INJURY)?

Answer 4

Infections: pneumonia, septicemia

• Inhaled gases: oxygen, smoke
• Liquid aspiration: gastric contents, near-drowning
• Drugs and chemicals: chemotherapeutic agents (bleomycin), other medications
• (amphotericin B), heroin, kerosene, paraquat
• Shock, trauma
• Radiation
• Transfusion related

Question 5

TABLE 15-1 – Classification and Causes of Pulmonary Edema

What can cause EDEMA OF UNDETERMINED ORIGIN ?

Answer 5

• High altitude
• Neurogenic (central nervous system trauma))

Question 6

The most common hemodynamic cause of pulmonary edema is ____________-

Answer 6

increased hydrostatic pressure ,
as occurs in left-sided congestive heart failure.

Question 7

Whatever the clinical setting, pulmonary
congestion and edema are characterized by ________

Answer 7

heavy, wet lungs.

Question 8

In Hemodynamic Pulmonary Edema where does fluid initially accumulates?

Answer 8

Fluid accumulates initially in the

• *basal regions of the lower lobes** because hydrostatic pressure is greater in these sites
• *(dependent edema).**

Question 9

What is the histological appearance of Hemodynamic Pulmonary Edema?

Answer 9

Histologically, the alveolar capillaries are engorged, and an intra-alveolar granular pink precipitate is seen.

Alveolar microhemorrhages and hemosiderin-laden
macrophages (“heart failure” cells)may be present.

In long-standing cases of pulmonary
congestion, such as those seen in mitral stenosis, hemosiderin-laden macrophages are
abundant, and fibrosis and thickening of the alveolar walls cause the soggy lungs to become
firm and brown (brown induration).

These changes not only impair normal respiratory function but also predispose to infection.

Question 10

Explain Edema Caused by Microvascular Injury

Answer 10

The second mechanism leading to pulmonary edema is injury to the capillaries of the alveolar
septa.

Here the pulmonary capillary hydrostatic pressure is usually not elevated, and
hemodynamic factors play a secondary role.

The edema results from primary injury to the
vascular endothelium or damage to alveolar epithelial cells (with secondary microvascular
injury).

This results in leakage of fluids and proteins first into the interstitial space and, in more
severe cases, into the alveoli.

In most forms of pneumonia the edema remains localized and is overshadowed by the manifestations of infection.

When diffuse, however, alveolar edema is an
important contributor to a serious and often fatal condition, acute respiratory distress
syndrome, discussed in the following section